Document – basic unit of information that can be indexed – json format

Shards (Sharding – Data partitioning) – subdivide index to multiple pieces called shards. Each shard is independent index and can be hosted on any node in the cluster. Split logical data over several machines – write scalability – control data flows

Replica shard (Data duplication) – copy of shard for failover & scaling purposes (search can be executes in all replicas in parallel) – read scalability – removing single point of failure (SPOF)

Concept – Distributed

first screen – shard and replica contract setup during index creation

On firing second node, it will look like second screen – green background are primary shards where data get indexed first and then to replica shards